For some bands of the late ’60s, herbs, pharmaceuticals, chemicals, and other perception-altering substances were fundamental to the music being played. Often, this is associated with San Francisco bands including the Grateful Dead, Quicksilver Messenger Service, and other bands that had a propensity to play on and on, improvising, adding, subtracting, modifying, noodling, drifting, daydreaming, and otherwise mesmerizing and apparently being mesmerized. And the audiences would engage with this in an appropriate, nodding, manner.
While this was primarily an American phenomenon, there were some British bands who undertook a somewhat analogous method of performance. But there was, in many instances of those that existed, a major difference.
Many of us in the U.S. hear someone with a British accent (with some exceptions, like, say, Liverpudlian) and think that the person is undoubtedly more sophisticated than their American brethren. It may be true. But not necessarily the case. Still, it is notionally convenient. While the American musicians were involved in long, seemingly endless jams, some of those on the other side of the Atlantic were involved in much the same thing. But the accent was different.
Rather than the American rock, some of the British bands were playing more jazz-influenced music. More sophisticated, as it were. One such British band was the Burroughsian-named Soft Machine.